flask/sqlalchemy - OperationalError: (sqlite3.OperationalError) no such table

You're supposed to initialize/create the tables first. Please read the Creating the Database article in the official Flask documentation:

Such systems need a schema that tells them how to store that information. So before starting the server for the first time it’s important to create that schema.

Here's Flask's example of using a schema SQL script to create the database, tables, etc:

sqlite3 /tmp/flaskr.db < schema.sql

The recommended way is to use db.create_all() within your app. For example, see: https://github.com/lily-mayfield/staticfuzz/blob/d2e54186f5639a06a5a796f0499a984ca8919ed7/staticfuzz.py#L403